Wifi is usually always active as is mobile data. Device is expected to do the switcharoo as necessary/possible. Not using SecureFishNet but using the built-in client which works great after having added the following line to the configuration file to ensure all traffic goes through the VPN:

Code:

redirect-gateway def1

"Wifikiller" application from OpenRepos but it didn't seem to work properly (or was not configured to work properly) so wifi stays on all the time, sadly.

Hi.

Man, this option made my day. I had it activated in the server side, but not in the client and a part of the traffic was routed via cellular data.... now everything goes through the VPN.

On your issue I have no clue (my xMPP client won't reconnect automatically when I switch from WiFi to cellular, and I don't know why.)

Going dead from 39% over 17 hours? On Jolla 1, that is absolutely 100% expected.
I do not know about SailX but it would not surprise me at all.

On SailfishX I've never seen more than 3-4% battery usage overnight (most times is 1-2% only), even with 7-8 open apps and an automated nightly rsync backup at 3:40am. On Jolla1 it was basically the same.
BTW I don't have yet installed any Android app on SailfishX.

Apple and Android phones were born as "monotasking" instead of multitasking because many stupid developers wasted CPU resources like there was no tomorrow and it was hard to explain to customers that their preferred apps kept wasting battery milliamperes like hungry piranhas surrounding a steak. A very few Android/iOS apps are allowed to do something when backgrounded (and only a few things like GPS updating, audio playing, network messaging, etc).

Monotasking automatically led developers to write even worse software - wasting CPU resources everytime they can - because they know that every time the app is not in foreground it's basically frozen.

Same here. Never allowed Android touch my Jolla. Still, 2% battery drop per hour is normal with no applications running, WiFi on and connected. With WiFi on and not connected this can increase four times.

The smallest overnight drop I have ever seen was 8%, and that was when I went to bed particularly late (long after midnight) and woke up as usual (about 05.30).

This is all on Jolla. But if others are reporting similar on their Xperias, then it is likely not a hardware issue.

__________________In particle accelerators atoms are indeed not only touching each others. But banging together in a massive explosive orgasm.
-- nieldk in a TMO post

Maybe this will show a comparison on battery life of the Jolla C and the XPeria X.

While my phone number hasn't been transferred from my old to my new operator, I carry the Jolla C around in my backpack only for SMS. The XPeria X is my main phone and phone calls to the Jolla C are redirected to the XPeria X.
On a day without touching the Jolla C at all, and moderate use of the XPeria X, I left the house in the morning with both fully charged, and returned home jn the evening with both at 70% of charge remaining.

Going dead from 39% over 17 hours? On Jolla 1, that is absolutely 100% expected.
I do not know about SailX but it would not surprise me at all.

F5121 standby on Android 7.1.1 was extremely good and shows the HWs capability if SW is optimized.
I had the device laying in the drawer from recieving, making updates and disposing it with ~80% into the drawer, 6 days later when flashing it still had more than 60%.
Now with sailfish, bit more than normal usage, full blown dalvik but without double tap hack i got ~2days out of it. Going to recharge it the first time this evening after putting it to use yesterday morning with 100% when my nano sim arrived.

EDIT, sfos may be not perfectly optimized for f5121, but it still amazed me that it stayed at 100% for around 5 minutes of usage until it went down to 99%.
On Jolla C, i unplugged at 100% and it went to 99% immediatly ever since i recieved it.